> Let's look at it this way. Consider a pizza and you are going to slice this pizza into 1, 2, 3, 4, ... slices. For each n, where n = 1, 2, 3, ... the interior angle of each slice will be 360/n, correct? And if for each n we sum up the interior angles we will get 360, correct?.>

In the algorithm I'm talking about, we triangulate the sphere suchthat each vertex has either 6 or 5 spokes coming out from each vertex,making a wheel-like pattern.

The perimeter is either a hexagon or a pentagon. If we bashed out thespokes, we would have like a soccer ball but with a vast number ofhexagons, yet still only 12 pentagons.

This is de-generalizing just a little, in that "all hexagons andpentagons" (were the spokes removed) only occurs in multiples of 3,counting the number of intervals (edges) from one pentagon center tothe next (this is called the "frequency" of the ball / sphere).

That's OK (to de-generalize a little) if it helps with the visualizations.

All very apropos of New Year's by the way, as the Times Square ball isone of these.

The higher the frequency, the more triangles, but it's still all sixslice and five slice pizzas, just more of them.

> As n -> infinity, the interior angles approach 0. The limit of 360/n as n approaches infinity is 0. Yet, the sum of the interior angles is always 360, or stated another way, n * 360/n = 360, a constant.>

The apex of each hexagon makes the pizza slightly convex / concavei.e. the center point is a not in plane with the points around the rim(the rim doesn't have to be all in a plane either). Every vertex is alocal apex i.e. is surround by a little less than 360 degrees.

The number of degrees around each vertex is never quite 360, becausewe're on a ball. But the triangles are so small, relatively, thatit's as flat as a bathroom floor (triangular tiles) exceptmathematically (and with careful measurement) we see that it isn't.Picture a ball the size of the Earth with triangular bathroom floortiles smoothly covering it -- they look almost perfectly equilateralexcept around pentagons (which may be hard to find are there are only12 of them).

Every vertex contributes some small positive finite amount to thegrand total of 720. 720 degrees apportioned to all these vertexes,really would create perfect flatness around each of them. The skinwould no any longer have convexity and this would not be a polyhedron.

> But you are missing a step when you stated your contradiction.>> You are asking why does limit(n) * limit(360/n) as n->infinity not equal the limit(n * 360/n) as n->infinity.>

360 is divided by either 6 or 5, but in such a way that | 360 - d |where d is the total degrees around v (vertex) > 0.

I can make | 360 - d | arbitrarily close to 0 as I increase thefrequency of the triangular mesh (more pizzas, but not more slicesaround each vertex -- that's 6 or 5).

Give me an epsilon, like .000000000000001 degrees, and I can give youa frequency that is less than epsilon, i.e. | 360 - d | < e.

> This is because the limit(n) as n->infinity does not exist, and thus, you can't multiply the limits.>

As the number of vertexes increases, | 360 - d | decreases as close to0 as we like. But it can never be 0, because all the vertexestogether contribute a grand total of 720 degrees (unchangingconstant).

This is what's known as Descartes Deficit, i.e. if you add up thenumber of degrees round each corner of a cube (90 + 90 + 90), thelocal deficit (the difference from 360) is 90 and 90 times the numberof vertexes is 720. This will be true of your octahedron,icosahedron, dodecahedron etc. etc., and true of your super highfrequency geodesic sphere.

> You did show that limit(360/n) exists and is zero.> You did show that limit(n * 360/n) exists and is 360.>> But your final statement actually involves limit(n), which you never showed existed, and indeed, doesn't exist.>> Bob Hansen>

n = number of vertexes on the sphere (note: if p = n - 2, then theratio of p:faces:edges = 1:2:3 if omni-triangulated)720 = constant angular deficit (all local deficits added) -- per Descartesd = number of degrees around each vertex (< 360 in all cases) butarbitrarily close|360 - d| = local angular deficit (a given vertex)

Sigma [local angular deficit] == 720all v

As the limit n increases without limit, local angular deficit -> 0,but sum total angular deficit remains fixed at 720.

Contradiction?

How could the sum of all the |360 - d| amounts be 720 (a constant) andyet each have 0 as a limit?

I guess you could say 720 * n * (1/n) --> 720 for any n (which isn'tquite the same thing), but it's interesting nonetheless how you canargue a limit of 0 at each vertex (perfect flatness at the limit), andyet know there's a fraction of 720 that's always keeping us from true0 (720/n approaches 0 too, as n -> infinity, I guess one would say).

Not a show stopper, but in the process we learn something aboutsubdividing a sphere, and maybe about calculus.